The present invention relates to a method and apparatus for winding a yarn. More specifically, the present invention relates to a method and an apparatus for winding a synthetic yarn by which a yarn can be wound without being broken and by which a stable winding operation can be done.
Conventionally, such methods and apparatus for winding a yarn are roughly classified into the following (a) and (b).
(a) Peripheral speed control type, disclosed in, for example, Japanese Utility model Application Laid-open No. Sho 58-71053 corresponding to U.S. Pat. No. 4,494,702, or Patent Application Laid-open No. Sho 49-20452.
(b) Tension control type, disclosed in, for example, Japanese Patent Publication No. Sho 55-25583.
Further, Japanese Patent Application Laid-open No. 58-42562 discloses a method and an apparatus for winding a yarn of a tension control type wherein the rotating speed of a bobbin holder is detected upon start of rotation of the bobbin holder so that the rotating ratio, i.e., the wind ratio, between the traverse motion and the rotation of the bobbin holder is kept at a predetermined value.
However, in these conventional apparatus, these exist the following problems.
In a yarn winding apparatus of the peripheral speed control type, high shoulders, which are generated between the start of winding operation and the completion of the winding operation, are increased in height as the amount of package increases, while the tension in yarn decreases, and accordingly, the yarn may be broken.
Further, in a winding operation of a yarn for industrial use, finishes applied to the yarn may adhere to the surfaces of a roller for detecting the peripheral speed or a draw roller, and the friction coefficient between the rollers and the yarn may be varied, or the tension in yarn may be changed as the winding operation is done due to the change of degree of polymerization of the yarn per se, and the yarn may be broken when the tension in yarn is excessively decreased.
The above-described phenomena often occur at a high speed winding or a low retraction yarn, and consequently there is a problem that productivity is low.
In a yarn winding apparatus of tension control type, response of the yarn tension detector is poor when a thin yarn, i.e., a yarn having a small denier, is wound since the tension in yarn is low, and accordingly, the apparatus cannot adequately respond to a sudden change of tension in yarn.
As described above, in conventional methods and apparatus for winding yarn, the peripheral speed control system and the tension control system have been independently used but have not been combined together.
Further, the method and apparatus disclosed in the above-described Japanese Patent Application Laid-open No. Sho 58-42562 are basically of the peripheral speed control type, and only during start of rotation of the bobbin holder, the rotating speed of the bobbin holder is detected in order to keep the wind ratio at a predetermined value, and accordingly, the tension control system and the peripheral speed control system are not combined while the yarn is wound.